Drainage works for weed control

Brothers Will and Charlie Langley are building on the solid foundation of a raised-bed, controlled traffic farming system that has allowed their family to better use some low-lying areas on their farm near Winchelsea, in Victoria’s southwest.

The Langley’s farming system is an excellent example of how alleviating soil constraints can benefit both crop production and weed suppression. In the process, they have implemented many of the WeedSmart Big 6 integrated weed management principles in a high-rainfall environment.

Their father, David Langley, is a founding member of Southern Farming Systems, and the family hosted the group’s first subsurface drainage and raised beds trials in the 1990s. These early trials showed that alleviating waterlogging using raised beds resulted in a yield increase of about 20 per cent.

After using 2 m beds for about four years, they moved to a 3 m raised bed, controlled traffic configuration developed over the last 25 years that has become the standard across most of the farm.

“In the 1990s, our business was 80 per cent sheep production and 20 per cent cropping,” says David. “With effective drainage now in place on areas that were too wet for cropping, we are now a majority cropping operation on 2430 ha of heavy brown clay soils and have sheep only on agistment.”

Their increased yield has more than compensated for the investment in drainage works. In 2020, Will received a Hyper Yielding Crops award for a wheat crop that came the closest to achieving its yield potential, followed the next year with the Highest Yield in 2021 award in the Southern Region.

The raised beds work like giant sponges in the Langley’s highly sodic clay soils, expanding and contracting to expel excess water from the paddocks. Their controlled traffic system keeps all traffic off the beds, reducing compaction of the crop root zone and extending the life of the beds.

“Keeping traffic off the beds preserves soil structure and keeps the profile aerated and moist. The crops have easy access to nutrients and develop a deeper root system,” says Will. “This system has boosted the farm’s income significantly and reduced the yield variability between years.”

Using a laser bucket and the GPS-guided T3RRA Cutta system, the Langleys have vastly improved drainage on their low-lying paddocks. The T3RRA Cutta software uses elevation maps to help the Langleys design and implement a drainage system that best suits their equipment and paddock topography. This industry-leading software makes it possible to move soil efficiently and cost-effectively.

“Weeds certainly take advantage of any areas of poor drainage,” says Will. “Fixing the drainage issue is the first step, and then crop competition can provide season-long weed suppression. We often have windy or wet periods during winter that reduce the optimal spray window, so crop competition is extremely important for us.”

They use a BOSS Agriculture tyned seeder with a bridge frame and parallelogram planting units, making it possible to consistently achieve the desired seeding depth. This results in even establishment, which promotes stronger crop competition. The Langleys also value the flexibility in pre-emergent herbicide choice that the tyne seeder allows.

The crops are sown into the beds on 25 cm row spacing, and the Langleys prefer to retain stubble to conserve nutrients and provide a weed-suppressive mulch layer.

“We found the transition to retaining stubble involves a period of nutrient tie-up, and this needs to be managed accordingly,” says Will. “Once the system is in place, the nutrient cycling is hugely beneficial. To minimise impediments to seeding, we harvest low and ensure an even chop and spread of residue.”

The Langleys apply fertiliser, lime and gypsum according to soil test results and work very closely with their agronomist to achieve their targeted nutrient requirements. Having broadcast lime and gypsum many years ago, they are now using variable rate technology to maintain their pH levels at around 5.5 across the farm.

“In 1994, we had paddocks with pH levels as low as 4, where nothing would grow,” says David. “Lime applications have brought those paddocks into production, and the ongoing addition of organic matter and gypsum have alleviated areas of sodicity on the farm.”

The Langleys also appreciate the impact of plant breeding programs on the competitiveness of their crops. They choose varieties with planting windows that allow them to optimise flowering times and apply pre-emergent and knock-down herbicides to manage the weed seed bank.

Topography and optimal drainage design determine the orientation of the raised beds. Consequently, some paddocks are sown east-west, and others are sown north-south. In Victoria’s southwest area, sowing east-west has dual advantages, providing wind protection of windrows and shading of the inter-row.

Their farming system keeps weed numbers low on their own country and has proven effective in reducing the weed seed bank on their leased land. Read the Langley’s full case study.

Crop planted on 250 mm rows on 3 m CTF raised beds.